The present disclosure relates generally to active clamp circuits and, more particularly, to active clamp and LC snubber circuits for switched-mode power converters.
Switched mode DC to DC converter power supplies are widely used to convert power from a source, such as mains power, to DC power supply for electronic devices. Switched mode DC to DC converters generally flyback and forward converter topologies. In both instances, the DC to DC converter employs a transformer and a switching device to couple energy to a secondary output. The transformer provides isolation as well as the ability to adjust the output voltage. However, due to its operation, a may suffer losses due to leakage inductance and excessive overshoot.
A well-known method to reduce these losses and limit overshoot is add an active clamp circuit switched mode power supplies. However, some known active clamp circuits require an integrated circuit (IC) to drive the clamp circuits. Other known active clamp circuits are self-driven, but are active during the full secondary stroke and intended for transition mode (quasi resonant) only power converters, which make these clamp circuits less suitable for certain modes of operation (e.g., Discontinuous Conduction Mode (DCM) operation). Moreover, most clamps and snubber circuits shunt leakage induced energy to ground and as a result reduce efficiency.
Accordingly, it is desirable to provide a switched mode power supply that overcomes losses due to snubber circuits and improves efficiency, particularly for power sensitive applications.